JPH09233127A - Method for data processing transporting efficiently multimedia data packet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To transport a fixed length or variable length multimedia data packet efficiently via a digital packet exchange network by configuring user data so as to be in complete matching with an ATM adaptation layer type 5. SOLUTION: A transmitter side merges plural multimedia data packets from a single user or plural users. Then a sub-header or a trailer merging user channel identification information and user data length information for merged multimedia data packets is added to the resultingly merged multimedia data packets. Thus, the entire payload is defined and the payload is transported on a network.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to digital networks, and more particularly, to a data processing method for efficiently transporting fixed-length or variable-length multimedia data packets via a packet switching network.

[0002]

The telecommunications carrier industry has begun to develop a concept called "broadband integrated digital communications network" or B-ISDN. This concept is considered to mean a carrier service that comprehensively provides high-speed communication to end users.

Various techniques have been developed for transporting information over networks. For example, there are packet switching and circuit switching techniques. In the former, the digitized data is arranged in so-called bit packets. In packet switching, bit packets may be of fixed length (in so-called asynchronous transfer mode (ATM), all packets called cells are of fixed length) or of variable length.

A fundamental advantage of packet switching over circuit switching is that different types of data can be statistically multiplexed on the link, thereby optimizing transmission bandwidth. The present invention seeks to retain this advantage under various circumstances. The present invention provides a frame relay (Fr
Although it can be applied to all packet switching techniques including Ame Relay), the embodiment of the present invention will be described to describe B-ISDN.
The method chosen to show how to deliver the service is
This is a method called "asynchronous transfer mode" or ATM.

The widespread acceptance of ATM is due to the fact that it is highly adaptable. ATM handles voice, data, images, video, high-quality sound, and all other heterogeneous communication traffic, including LAN (local area network) and WAN (wide area network).
Can be used on both sides.

ATM does not process voice as efficiently as concurrent networks. It doesn't handle video as easily as concurrent transfers. It is not always the packet transfer mode (Packet Transfer Mod).
e) or does not process data as efficiently or effectively as frame relay systems. Also, it can cause problems in environments with high error rates. Nevertheless, all of the various multimedia data mentioned above can be combined and transported over the same network, which is a great advantage over other networks. Ie, using many specialized equipment,
The advantage is that they can use a single device that performs all the functions rather than letting them perform different functions.

The important basic concept of ATM is as follows.

All information (voice, image, video, data, etc.) is a "cell" (herein referred to as an ATM cell).
Transported through the network in very short fixed length blocks (48 data bytes plus a 5 byte header) called.

Information flows along a path called a "virtual channel" (VC) set up as a series of pointers through the network. The cell header contains an identifier that links the cell to the correct path to bring the cell to its destination. Cells on a particular virtual channel always take the same path through the network and are sent to their destination in the order in which they were received.

ATM is designed so that simple logic elements based on hardware can be used at each node to perform the exchange. For 1 Gbps links, new cell arrivals and transmissions occur every 0.43 microseconds. There is little time to decide what to do with the arriving cell.

At the edge of the network, the network port or access node, user data frames or packets are divided into cells. Continuous data streams such as voice and video are assembled into ATM cells. At the destination side of the network, the user data frame is reconstructed from the received cells and presented to the end user in the form passed to the network. This adaptation function is considered to be a part of the network function, but the ATM adaptation layer (Adapt) is used.
It is performed in a higher layer called station layer (AAL). Devices that perform such functions at the edges or ports of the network are already in use,
For example, a complete specification is defined by the international standard as an ATM adaptation layer (AAL).

The ATM cell switching network only inspects cell headers and simply discards erroneous cells. The adaptation function AAL is external to the switching network, and usually depends on the type of traffic, but usually about data traffic.
It checks the data frame for errors and discards the entire frame if an error is found. In any case, A
The TM network does not try to recover the error by retransmitting the information. This function is left to the end-user equipment and depends on the type of traffic being performed and the adaptation layer being used. For example, end-user equipment has been proposed that recovers discarded audio data using so-called interpolation / extrapolation techniques.

For information on ATM networks, see, for example, "High Speed Networking".
Technology: An Introducto
rySurvey ”(June 1993, Docum)
ent Number GG24-3816-01, I
BM International Technica
l Support Center, Raleigh)
It is described in.

Information regarding ATM standards is provided in the International Telecommunication Union (ITU) Recommendations.

As described above, the asynchronous transfer mode (AT
M) is believed to be inefficient under many circumstances. For example, for voice transport applications, a private branch exchange (PBX) servicing multiple telephones is connected to a voice server, which encodes and compresses digitized user voice. Global System for Mobile
e) When applied to the (GSM) telephone system, a 160-byte-long data frame (or packet) is compressed by a factor of 5, but may be compressed by a factor of 8. Thus, a data packet transported in ATM cells (48 data bytes long payload plus 5 bytes long header) has 32 bytes or 20 bytes of payload data. Therefore, ATM
One data packet provided to the network port does not fill the payload field of one ATM cell.

In other words, it is necessary to fill each ATM cell with a dummy byte (16 or 28 bytes per cell) or combine the user frame into several consecutive ATM cells (note: so-called bytes , In the International Telecommunication Union standard terminology, called "octet"). The first solution leads to inefficient bandwidth occupancy and should obviously be avoided.

Then, the second solution remains.

When processing a plurality of such frames (or packets) in a normal ATM network,
It is easily imagined that various problems will occur. This is especially the case if the frame is of variable length or shorter than the normal ATM cell payload, such as a frame coming from a voice server performing a silence removal operation. This is the same whether the frame is given directly to the ATM network or via another network (eg, a packet switched access network). On the other hand, the standard requirements for the ATM adaptation layer (ALL) have been redefined so that user data packets, whether fixed length or variable length, can be completely encapsulated and transported as an ATM cell stream. It is also possible to do it. If you follow this method, some of your existing network hardware will be unusable,
This obviously causes many serious problems from a practical point of view.

The current International Telecommunication Union (ITU) standard collects short packets (which may be of variable length) as composite packets in ATM cells and allows the ATM adaptation layer at the receiving end of the network to It cannot be said that particular attention is paid to the problem of allowing individual packets to be easily retrieved from the ATM cell stream.

Various solutions have been proposed which recommend the creation of new AAL standards. Such a proposal means not only a modification of the standard but also a modification of the hardware currently used.

[0021]

SUMMARY OF THE INVENTION An object of the present invention is to provide a data processing method for efficiently transporting fixed-length or variable-length multimedia data packets via a digital packet switching network. .

Another object of the present invention is that the data packet is A
Transport fixed or variable length data packets by efficiently putting the data packets into conventional ATM cells, whether provided directly to the TM network or via a so-called access network. It is to provide a method of data processing.

Yet another object of the present invention is to provide a fixed or variable length data packet to a conventional AT with minimal delay.
It is to provide a method of data processing for transporting to M cells.

Yet another object of the present invention is to reduce delays by allowing either so-called blocking techniques or multiplexing techniques, or both, to be used in the same network when sending user data packets. Minimize and optimize bandwidth usage.

Yet another object of the present invention is to provide fixed or variable length data packets based on the standard ATM Adaptation Layer Type 5 (AAL5) and thus adapted to currently used ATM network hardware. Is to provide a method for efficiently transporting a packet over an ATM network.

[0026]

These and other objects, features, and advantages of the present invention will be considered in the following detailed description with reference to the accompanying drawings, which detail preferred embodiments of the invention. It will be obvious.

The present invention provides a data processing method for efficiently transporting fixed-length or variable-length multimedia packets via a digital packet switching network that transmits fixed-length packets. This method concatenates a plurality of multimedia data packets sent from a single or a plurality of users on the transmission side, and user channel identification information (CID) and user data length of each concatenated multimedia data packet. A subheader or trailer in which (UDL) is concatenated is added to the concatenated multimedia data packet to define the entire payload, and this payload is transported on the network.

[0028]

FIG. 1 is a block diagram showing an ATM network connected to conventional equipment for transmitting and processing GSM voice information or fixed station originated voice information. It should be noted that the audio information is taken up merely for the sake of illustration and to simplify the description of the embodiments of the invention. The invention is by no means limited to audio information and is equally applicable to multimedia containing audio or image data, for example.

The network of FIG. 1 includes three intermediate nodes (node 1, node 2 and node 3) and two access nodes (node A and node B) at the edge of the network. These nodes are tracks or trunks TK1, TK2, TK3 ,. . . . Interconnected by.

PBX (A) is connected to access node A, and PBX (B) is connected to access node B. These PBXs have n telephone sets TA1 and TA, respectively.
2 ,. . . , TAn, and TB1, TB2 ,. . . ,
Serve TBn.

The nodes A and B have a voice server function, which compresses voice data and enables efficient use of bandwidth in the network.

Further, a GSM base station is connected to node A. This base station comprises mobile stations MS1, MS2 ,. . . GSM compressed data can therefore be transported over an ATM network if desired.

As shown in FIG. 1, PBX and GS
The M base station is via a packet switched access node,
Or you can connect directly (see the dashed line) to the ATM network. As mentioned above, data traversing network nodes and trunks within an ATM network is derived from image or voice sources,
These sources are not shown for simplicity of illustration.

As mentioned above, in an ATM network, data is usually arranged as a plurality of ATM cells. Each cell contains a 48 byte long payload and a 5 byte long header. That is, the ATM cell is predetermined as a fixed length. However, the data provided to a network port, eg node A, is often of variable length and its length is often shorter than a typical ATM cell payload. This variable length packet has to go through several paths. For example, ATM networks are configured to include a number of virtual channels (VCs) on a given virtual path (VP) along a network trunk. Data from different users is defined by a particular channel identification (CID) and sent to the same virtual channel and can therefore be combined by a multiplexing operation. But,
It is also possible to block multiple variable length compressed voice packets from the same user. As a result, a message of, for example, 400 bytes may be generated by concatenating short variable-length user packets. Not only are each user packet shorter than 48 bytes, they may be of variable length. The problem faced here is how to encapsulate these short user packets into an ATM cell stream for efficient transport. To achieve efficiency, the ATM cells must not be filled with extra data and modifications to existing network hardware must be avoided.

The present invention is an International Telecommunication Union standard applicable to currently operating ATM networks, specifically ATM Adaptation Layer Type 5
The above object is achieved by providing a method of constructing or concatenating user data so that it completely matches (AAL5).

The structure of AAL type 5 is shown in FIG. Figure 2 shows two service access points (SAP)
Define various sublayers between. Original Convergence Sublayer
(CS) is a service-specific convergence sublayer (Service Specific Co).
(Nevergence Sublayer) (SSCS)
Common part Convergence sublayer (Common
Part Convergence Sublay
r) (CPCS). The third sublayer is Segmentation and Assembly.
and Reassembly (SAR). The sublayers cooperate to provide AAL type 5 service from top to bottom on the transmit side and from bottom to top on the receive side. Transmission means data segmentation, and reception means data assembly.

In the transmit direction, and with currently available hardware, given a variable length payload, AA
The hardware defined by L5 provides a packet with a structure as shown in FIG. CPCS-SDU
CPC used to carry (or user data)
The S-Protocol Data Unit (CPCS-PDU) payload is optionally filled with fields from zero to three bytes long, followed by a CPCS-PDU trailer. The CPCS-PDU trailer includes:

-CPCS user to user (CPCS-
UU) First field containing indication. The CPCS-UU field is used to transparently transfer CPCS user-to-user information. In the current practice, CPCS-UU is set to zero. In the present invention, the CPCS-UU includes an SSCS trailer offset (STO) field defined for transferring information from the SSCS sublayer, and a reservation (RES) field that can be used for other purposes.

Common part indicator (Commo
n Part Indicator (CPI) field. This is used, for example, to align the CPCS-PDU trailer to a given length. This field is set to zero in the current practice.

Length field. This field is C
Used to code the length of the PCS-PDU payload field.

CRC field. This field stores the CRC-32 that performs data validation,
Used to detect bit errors in CPCS-PDU. The CRC field includes a CPCS-PDU payload and a PAD field.
The value of the CRC calculation that is performed on the entire contents of

FIG. 4 is a schematic diagram of the AAL and ATM layers operating in accordance with the present invention. Here, n connection end points CEP1, CEP2 ,. . . , CEPn is assumed to be present. The service-specific convergence sublayer is a service variable unit or a service data unit (Service Data Unit) from the corresponding connection end point.
ta Unit) AAL SDU1, AAL SDU
2 ,. . . , AAL SDUn to connect SSCS-P
Operates as a DU payload. Although not clear from FIG. 4, in the preferred embodiment of the invention, this concatenation process involves a new AAL S on a 4-byte (ie, 32 bit) boundary following the end of the previously concatenated AAL SDU.
This is done by initiating DU concatenation. A plurality of concatenated AAL SDUs are encapsulated with an SSCS trailer (or subheader) (with a trailer added), and an SSCS PDU (Protocol Data)
Unit) Payload.

In the present invention, the 4-bit long SSCS trailer offset (STO) is used to calculate the offset of the starting point of the SSCS trailer. The value of this offset is defined as a multiple of 4 bytes
Let the S trailer start at a 32-bit (ie, 4 byte) alignment point. In other words, the starting point of the SSCS trailer is the end of the CPCS-SDU aligned with the next 32nd bit boundary. Furthermore, STO
The field indicates that the data is processed according to the present invention.

Various codes may be adopted as the contents of the STO field. For example, the code is defined to point to: -STO = 0 no trailer-STO = 1 SSCS Indicates that the trailer is between 1 and 4 bytes long. -STO = 15 SSCS trailer has 57 bytes and 6
Indicates that the length is between 0 bytes.

SSCS PDU with subheader added
The payload is a CPCS-PDU as shown in FIG.
Define the payload or CPCS-SDU. SSC
The S payload contains various AAL SDUs (ie AAL SDU1, AA) filled with zero to three byte length PADs so that the concatenation described above starts on a 32-bit boundary.
L SDU2 ,. . . , AAL SDUn). Then for the SSCS payload i = 1,
2 ,. . . , N to sequentially set the list of channel identification information (CIDi), i = 1,
2 ,. . . , N various user data lengths (UDL
An SSCS trailer (or subheader) is created to specify i). As shown in FIG. 5, SSCS
Trailers are CID1, UDL1; CID2, UDL
2 ;. . . It is assembled by connecting CIDn and UDLn.

As a refinement, the default channel identification information (DCID) or default user data length (DUDL) may be defined. These default codes save transmission bandwidth and improve processing time.

The protocol for changing the default value is defined in CID 255. This protocol uses two messages. One is a request message for changing the default value, and the other is a confirmation message. During the time window between transmitting the change request and receiving the corresponding confirmation, the sender of the network checks that there is no default value. next,
The explicit CID and UDL are used in the SSCS trailer and data transmission continues. Therefore, traffic is uninterrupted.

More specifically, the channel ID field does not exist under the following conditions. If there is a single AAL5 SDU and it uses the default channel. In this case, there is no SSCS trailer. -When using the default channel without using the default user data length. In this case, AAL5
There is a user data length field associated with the SDU.

Note that there is always at least one control field per AAL5 SDU when multiple SDUs are blocked in one PDU.
Thereby, the SDU to which each control field applies can be identified.

As for the User Data Length (UDL) field, it does not exist under the following conditions. -When there is one SSCS payload. in this case,
The length field in the AAL5 CPCS trailer is A
Identifies the length of the AL SDU. -When the user data length is the default value.

Further, each field is a so-called basic encoding rule.
Coded by (BER). Therefore, the channel identification information is coded in the range 130 to 255,
CID = 255 is used as a signaling channel to change the default value. In other words, it allows the default value to be adapted to the current operating conditions.

The code range from zero to 129 is used to define the user data length. -If the length of the user data field is less than or equal to 128, the UDL is one byte long, which represents the length of the SSCS payload. If the user data field length is greater than 128, then the UDL is 3 bytes long and is coded as follows: Bytes 1 = 129 bytes 2-3 = length of user data field

Furthermore, the basic coding rules are applied as follows. -If there is only one SSCS payload associated with the default channel, then there is no SSCS trailer and STO = 0. In this case, AAL5 CPCS
The length field in the trailer represents the length of the AAL SDU. The SSCS trailer contains at least one control field per SSCS payload if there is only one SSCS payload associated with the non-default channel or if there are multiple SSCS payloads.

This makes it possible to identify the SDU to which each control field applies.

If the channel is the default value and the user data length is the default value, only the CID is present. • If the channel has a non-default value or the user data length has a non-default value, then only the fields associated with that non-default value are present. If the channel has a non-default value and the user data length has a non-default value, both CID and UDL fields are present and the CID field is UDL.
Set before the field. As a result, -If the CID is followed by the UDL, these two apply to the same SSCS payload. If UID is followed by CID, UDL is the previous SS
Associated with CS payload, CID is later SSCS
It is associated with the payload.

Returning to FIG. 4, after the CPCS-PDU payload has a CPCS-PDU trailer (or second trailer) attached, the process proceeds to the normal AAL type 5 "segmentation and assembly" (SAR) layer. Can be segmented and assembled. The SAR SDU provided by the CPCS layer defines a generic payload, which is a plurality of SARs that are 48 bytes long.
It is segmented into PDUs. Each SAR PDU becomes an ATM cell payload for the ATM layer. Each ATM cell payload is encapsulated with an ordinary ATM header having a length of 5 bytes to form an ATM cell.

It should be noted that, depending on the application, the second trailer only needs an STO indication and the resulting generic payload is ready to be sent on the network.

Returning to ATM, it can be seen that each ATM cell contains one or more AAL SDUs or parts thereof. The last ATM cell is the SSCS trailer,
The following fill bit (if required) and the normal AAL5 trailer (normal CRC for validity check)
32 is included).

Therefore, the hardware already used in the normal ATM network based on the AAL5 application does not require any modification. Thus, the present invention provides a very convenient method,
There is no problem of having to redefine the standard and change existing hardware. Those skilled in the art of digital networks will appreciate the benefits of the present invention.

Further, FIGS. 7 and 8 (these figures are
As can be seen from the arrangement relationship shown in FIG.
The algorithm or software implementing the method of the invention is fairly simple.

As described above, the user data (AAL
SDU1 ,. . . , AAL SDUn) is SSCS P
It is concatenated in the DU payload. This connection is fairly simple. However, to further simplify the process, the next block (ie, AAL SDUi + 1) is AAL no matter what the length of AAL SDUi is.
It is aligned at a 32-bit multiple following the SDUi concatenation start point. If necessary, fill bit is AAL S
Inserted at the end of DUi.

Referring now to FIGS. 7 and 8, there is shown a flow chart for creating an SSCS trailer (performed at the sender of a user-to-user communication process).

First, in consideration of efficiency, a predetermined time limit limit value is set for the connecting operation. Therefore, first the timer is set to zero, packet counting is started (N = 0) and the scan index I is set to one. This is done in step 1. Then the system is the first A
Take AL SDU and increase N by one unit. Corresponding channel identification information (ID) is the default channel ID
Is tested against (step 2). If the test result is yes (Y), the next test is executed (step 3). This new test is done to check if the considered user data length is equal to the default value selected for the considered channel.
If the result of this test is yes, the CO sent
SSCS trailer byte (“octet”) that represents (I)
, Also referred to as channel identification information, and I is incremented by 1 unit (step 4). The process then waits for the next AAL SDU (step 5). But,
If the result of the test in step 3 is no (N), another test is performed to check if the user data length considered is smaller than the decimal value 129 (step 6). If the result of this test is yes, then a trailer pit (CO (I)) to be transferred is created (step 7) to give a value for the user data length and I is incremented by one unit. If the result of the test performed in step 6 is no, the trailer byte to be transferred is equal to 129 and the next byte defining the user data length (ie CO (I + 1) and CO (I + 2)) is Made (steps 8 and 9). Therefore, I is increased by 3 units. Then the process comes in next AA
Go to step 5 of waiting for LSDU.

Here, if the result of the test in step 2 is NO, the channel identification information (CID) under consideration is considered.
The byte CO (I) is coded according to (N)) (step 10) and the user data length is tested against the user data length default value for the corresponding channel (step 11). If the result of this test is yes, then I is incremented by 1 and the process proceeds to the next AAL
Go to step 5 to wait for the SDU. Otherwise, the user data length considered is a decimal value 12
Another test is made to see if it is less than 9 (step 12). If the test result is yes,
The user data length is encoded in the next byte (step 13), I is incremented by 2 units and the process goes to step 5. However, if the result of step 12 is no, the byte CO (I + 1) is coded 129 (step 14) and the user data length (UDL) considered is taken into account.
The next two bytes are used to code (N)) (step 15), I is incremented by 4 units, and the process goes to step 5 waiting for the next AAL SDU. Before fetching the next AAL SDU, the timer is always checked against the time limit limit.
If the timer has not reached the predefined time limit, the process loops back to fetch a new AAL SDU and executes all of the trailer processes described thus far. If the timer has expired, a new test is made (step 16 in Figure 9). That is,
If count N = 1, no SSCS trailer is needed and the STO field is set to zero (step 1
7). But if the test in step 16 is no,
SSCS trailer is connected (step 18), STO
The value is set to the trailer length divided by 4 and it is written to the CPCS-UU (steps 19 and 20). At this point, the trailer is created.

In addition to the advantages described above for the present invention, the operation of the receiving side according to the present invention is also completely in line with existing standards and therefore requires no special hardware modifications and is even simpler. It can be implemented in an algorithm.

The standard functional model of AAL type 5 on the receiving side is shown in the schematic diagram of FIG. even here,
No changes need to be made for assembly layer operations, including SAR and CPCS operations. Therefore, received A
The TM cell payload is concatenated into a CPCS-SDU and if the content of the STO field is not zero then SSC
SSCS with S PDU trailer or subheader
It is passed to the SSCS layer as a PDU payload.
The rest of the process is performed at the SSCS layer level and various AAL SDUs are reconfigured and designated and passed to the user or other network.

The operation of the SSCS layer may be executed according to the flowchart of FIG. It should be noted here that all payloads are concatenated to the beginning of the frame under consideration and the channel ID and unit data length are defined in the SSCS trailer. The SSCS PDU payload may be filled and the SSCS trailer has been added to it. The processing of the algorithm will now be described with a focus on scanning this trailer byte by byte.

The process begins by setting the counter N, which indicates the number of concatenated AAL SDUs, to one. Next, it is checked whether the content of the STO field is zero. If zero, the channel ID being sought is equal to the default channel ID M, and the user data length is equal to the length of the CPCS-PDU. Then the process ends.

If the content of the STO field is non-zero, the SSCS trailer field at the SSCS layer operation level is present in the received frame,
Its contents are scanned byte by byte. This pit is designated as the control octet (CO (i)). i = 1,
2, 3,. . . , K, indicating the current position in the SSCS trailer to be scanned, k defining the length of the SSCS trailer derived from the contents of the STO field.

The process begins by setting i = 1 and reading the indicated control octet (step 1
01). When CO (i) does not exist, that is, i is k
If so, the process ends. But CO
If (i) is present, its content value is tested against the binary value of 129 (step 102). If CO
If (i) is less than or equal to 129, the current CI
D (ie CID (N)) is equal to the default value (ie DCID) selected for the channel identification information (step 103). Next, CO (i) is 129
Is tested (step 4).
If they are equal, then, as mentioned above, the current user data length is the next two bytes CO (i + 1) and CO (i +).
It can be seen that it is coded in 2). These bytes are read and stored and the pointer index i is incremented by 3 units (step 105). N is incremented by one unit and the process loops back to step 101 where it reads a new control octet. Step 1
If CO (i) considered in 04 is a value different from 129, the currently read byte CO (i) indicates the value of the user data length, this value is stored and i is incremented by 1 unit. Then, (Step 106), N is incremented by one unit, and the loop is returned to Step 101.

If, however, the result of the test performed in step 102 is no, the process checks whether CO (i + 1) is present, ie i + 1 is less than or equal to k (step 107). If no, set the channel identification information equal to the value of the considered byte CO (i) and set the user data length value equal to the default user data length selected for the considered channel ID. After setting (step 108), SSC
The scanning of the S trailer ends. Otherwise, CO
(I + 1) is read and compared with the value 129 (step 109). If CO (i + 1) is greater than 129, byte CO (i) gives CID (N) and the current user data length is set to the default value defaulted for the channel under consideration (step 110). Then both i and N are incremented by one unit and the process loops back to step 101 to fetch the next CO (i).

If the result of the test performed in step 109 is yes, then the current CO (i) defines the value of the channel identification information (step 111).

In step 112, CO (i + 1) is 1
A new test for equality to 29 is done. If equal, the user data length is represented (113) by the next two consecutive bytes CO (i + 1) and CO (i + 2) in the SSCS trailer.
i is incremented by 4 units, N is incremented by 1 unit, and the process loops back to step 101. If the result of the test performed in step 112 is no, CO
(I + 1) gives the value of the user data length UDL (N) (step 114). Then i is increased by 2 units,
N is incremented by one unit and the system loops back to step 1.

As mentioned above, the present invention can be applied to various combinations of users by performing so-called "blocking" or "multiplexing" functions. If the blocking function is used, multiple AAL SDUs coming from a single user are concatenated into one AAL PDU.
Can be put in. With the multiplexing function, different AA
Multiple AT data streams from L users
Multiplexed to M connections. Each data stream is identified by a particular connection endpoint (CEP).

12 to 15 show four possible combinations of blocking and multiplexing functions.

A single AAL SDU coming from a CEP
It is clear that no blocking or multiplexing functions are performed when the is transported in a single AAL PDU. In that case, CEP1 is the SAP's only CEP or the SAP's default CEP.

When the blocking function is implemented, multiple AAL SDUs coming from a single CEP may be combined into a single AAL.
Transported in PDU. CEP1 is SA
It is either the CEP of P or the default CEP of SAP. A UDL field is required to identify the length of each user data block or packet.

When the multiplexing function is performed, different C
Multiple AAL SDUs coming from EP are multiple AAL Ps
Transported in DU. A CID field is needed to identify the channel ID associated with each CEP.

When both multiplexing and blocking functions are implemented, multiple AALs coming from different CEPs
SDUs are transported in a single AAL PDU. Both the CID and UDL fields are needed to identify the channel ID associated with each CEP and the user data length for each user data block. The basic encoding rules define which function (blocking, multiplexing, both, or neither) is performed for each AAL PDU.

The method of the present invention is very flexible and does not require negotiation between two peer AALs about which function to use.

From the above description, it is also possible to select different basic coding rules and numerical parameters for the present invention, and the invention may be implemented in one or more media without departing from the spirit of the invention. It can be applied to.

In summary, the following items are disclosed regarding the configuration of the present invention. (1) A data processing method for efficiently transporting a multimedia data packet on a digital packet switching network, wherein a fixed-length or variable-length data packet issued by a single or a plurality of users on the transmission side. User channel identification information (CID) of each of the above-mentioned data packet payloads, which are formed by linking payloads
And a user data length (UDL) are concatenated, a sub-header or trailer is added to the concatenated data packet payload, and information for identifying the length of the trailer is further added to define the entire payload. A method of data processing, characterized in that the payload of the packet is transported by the packet switching network. (2) A data processing method for efficiently receiving a fixed-length or variable-length multimedia data packet sent via the packet switching network according to the method described in (1) above. A user channel identification information (CID) and a user data length (UD) of each data packet assembled from the payload are assembled.
A method of data processing, characterized in that the assembled payload is divided into original fixed-length or variable-length payloads based on information of the trailer connecting L). (3) A fixed length or variable length multimedia data packet is efficiently transmitted through an ATM network for sending a fixed length ATM cell including a fixed length ATM (asynchronous transfer mode) cell payload field and a fixed length cell header field. A method of data processing according to (1) above, wherein the multimedia data packets sent from one or more users are concatenated at the sender side by the International Telecommunication Union (ITU) to ATM.
A so-called Service Specific Convergence Sublayer (SSCS) Protocol Data Unit (PDU) payload, as defined for adaptation layer type 5, with user channel identification information (CID) and user data length (CID) of each concatenated data packet. UD
L) the trailer connecting the SSCS PD
A so-called Common Convergence Convergence Sublayer (CPCS) Service Data Unit (SDU) or CPCS PDU payload is generated by appending to the U payload, and the normal CPCS protocol as defined by the International Telecommunication Union (ITU) standard. Data Unit (PDU) Trailer to CPCS PD
A normal ITU segmentation and assembly (SAR) layer service data unit (SDU) is generated by appending to the U payload, and the SAR SDU is divided into a plurality of segments having a normal ATM cell payload length.
A normal ATM cell that is sent over the ATM network by partitioning the, and generating a normal ATM header and adding it to each of the segments. (4) A data processing method for efficiently receiving a fixed-length or variable-length multimedia data packet sent via an ATM network according to the method described in (3) above, which receives the ATM cell and receives the ATM cell. The header is removed, the ATM cell payload is taken out, the ATM cell payloads taken out above are concatenated, and the CPC
Original CPCS P with S PDU trailer attached
Play the DU payload, find a trailer in the CPCS PDU payload that contains the original user data length (UDL) and user channel identification information (CID) added to the so-called SSCS PDU payload and scan the trailer. And decoding the UDL and CID to reproduce the original data packet from the SSCS PDU payload. (5) The data processing method according to (3) or (4), which efficiently transports a fixed-length or variable-length multimedia data packet via the ATM network. A method of data processing characterized in that it is connected to an ATM network either directly or via a so-called packet switched access node. (6) A data processing method for efficiently transporting a data packet according to the method described in any one of (1) to (5) above, wherein the original data packet is a normal ATM cell payload. A method of processing data, characterized in that it comprises packets that are shorter than their length. (7) A method of data processing for efficiently transporting fixed-length or variable-length data packets according to the method described in (5) or (6) above, wherein the CPCS
The concatenation and addition to generate a Service Data Unit (SDU) payload is initiated at a boundary that is a multiple of a predetermined number of bytes from the payload start point and, if necessary, of the data packets or trailers to be concatenated. Method of data processing, characterized in that padding bytes are inserted between. (8) A method of data processing for efficiently transporting fixed-length or variable-length data packets according to the method described in (6) or (7) above, wherein the user channel identification information or user data length A method of processing data, characterized in that a default value is defined for. (9) In the data processing method according to (8) above,
Based on the user's request and the confirmation of the receiving side, the default value is changed without any interruption of traffic between them, and then the process is characterized by the fact that the process uses an explicit value. the method of. (10) A method of data processing for efficiently transmitting a data packet through an ATM data network, for indicating that the data packet has been transferred according to the method described in (3) to (8) above. CPCS PDU
A method of data processing, characterized in that a so-called service trailer offset (STO) field in the trailer field is used, whereby the presence of the trailer and its length are specified. (11) A method for efficiently receiving a data packet transmitted through an ATM network according to the method described in (10) above, which monitors a coded value in the service trailer offset field to perform a receiving operation. A method for processing data, characterized in that it is controlled. (12) A method for efficiently transmitting or receiving a data packet according to the method described in any one of (3) to (11), wherein the user data length (UDL) and the user channel identification information ( Method of data processing, characterized in that the coded fields for CID) are defined to be mutually exclusive according to the so-called basic coding rules. (13) A method for efficiently transmitting and receiving multimedia data packets according to the method described in (12) above, wherein the transmission is performed in a multiplexing mode or a blocking mode. The default code that specifies whether one mode is being run, or not being in either of these two modes, is in C above.
A method of data processing characterized by being placed in a PCS PDU trailer.

[Brief description of drawings]

FIG. 1 shows an ATM network in which the present invention can be implemented.

FIG. 2 International Telecommunication Union (IT) applied to the present invention.
It is a figure which shows the layer structure of the ATM adaptation layer 5 defined by the standard of U).

FIG. 3 is a diagram showing a CPCS-PDU format for AAL type 5.

FIG. 4 is a conceptual diagram when the present invention is applied to a standard (AAL type 5 functional model).

FIG. 5 is a conceptual diagram of the format of a CPCS layer payload according to the present invention.

FIG. 6 is a diagram showing an arrangement relationship between FIGS. 7 and 8;

FIG. 7 is a diagram showing a part of a flow chart when the present invention is implemented on the transmission side of an ATM network.

FIG. 8 is a diagram showing another part of the flowchart when the present invention is implemented on the transmission side of the ATM network.

FIG. 9 is a diagram showing still another part of the flowchart when the present invention is implemented on the transmission side of the ATM network.

FIG. 10 is a diagram showing the functional mode of AAL type 5 on the receiving side of the International Telecommunication Union standard.

FIG. 11 is a diagram showing a flowchart when the present invention is implemented on the receiving side of an ATM network.

FIG. 12 is a diagram showing a user data payload applicable to the present invention when both the blocking function and the multiplexing function are not used.

FIG. 13 is a diagram showing a user data payload applicable to the present invention when a blocking function is used.

FIG. 14 is a diagram showing a user data payload applicable to the present invention when the multiplexing function is used.

FIG. 15 is a diagram showing a user data payload applicable to the present invention when both the blocking function and the multiplexing function are used.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Lauren Nikola France 06270, Villeneuve Ruvele Hamillos Soleil Numero 20 Les Spire (72) Inventor Gros des Garins France 06800, Cagnes Mail 56 Avenue des Tilliers (72) ) Inventor Bernard Pucci, France 06800, Sde Globoo 69 Le Oats des Tilliers

Claims (13)

[Claims] 1. A data processing method for efficiently transporting multimedia data packets on a digital packet switching network, comprising a fixed-length or variable-length data sent from a single or a plurality of users at a transmission side. The data packet payloads are concatenated, and the user channel identification information (C
ID) and user data length (UDL) concatenated subheader or trailer is added to the concatenated data packet payload, and information for identifying the length of the trailer is further added to define the entire payload, A method of data processing, characterized in that the entire payload is transported by the packet switching network. 2. A method of data processing for efficiently receiving multimedia data packets of fixed length or variable length sent via said packet switching network according to the method of claim 1, said received data being received. A network payload is assembled, and user channel identification information (CID) and user data length (U) of each concatenated data packet.
DL) based on the information of the trailer linking
A method of data processing, characterized in that the assembled payload is divided into original fixed-length or variable-length payloads. 3. Efficient fixed or variable length multimedia data packets over an ATM network for sending fixed length ATM cells including fixed length ATM (asynchronous transfer mode) cell payload fields and fixed length cell header fields. The method of data processing according to claim 1, wherein the multimedia data packets originated from one or more users are concatenated by the International Telecommunication Union (ITU). A
So-called Service Specific Convergence Sublayer (SSCS) Protocol Data Unit (PD) as defined for TM Adaptation Layer Type 5
U) As the payload, the SSCS is used to connect the trailer connecting the user channel identification information (CID) and the user data length (UDL) of each connected data packet.
A so-called Common Convergence Convergence Sublayer (CPCS) Service Data Unit (SDU) or CPCS PDU by adding to the PDU payload
The payload is generated and a conventional CPCS Protocol Data Unit (PDU) trailer as defined by the International Telecommunication Union (ITU) standard is added to the CPCS.
By adding to the PDU payload, the normal I
Generate TU Segmentation and Assembly (SAR) Layer Service Data Units (SDUs) into multiple segments with normal ATM cell payload length.
By segmenting the SDU and generating a normal ATM header and appending it to each of the above segments, the A
A method of data processing, characterized in that a normal ATM cell is sent which is sent over a TM network. 4. A data processing method for efficiently receiving fixed length or variable length multimedia data packets sent via an ATM network according to the method of claim 3, wherein said ATM cells are received. ATM
Remove the header and take out the ATM cell payload,
The extracted ATM cell payloads are concatenated to form C
Original CPCS with PCS PDU trailer attached
Plays back the PDU payload, so called SSCS PD
Original user data length (UD) added to U payload
L) and a trailer containing user channel identification information (CID) in the CPCS PDU payload,
A method of data processing, characterized in that the original data packet is reproduced from the SSCS PDU payload by scanning the trailer and decoding the UDL and CID. 5. The method of data processing according to claim 3 or 4, wherein fixed-length or variable-length multimedia data packets are efficiently transported through the ATM network. A method for processing data, characterized in that it is connected to an ATM network via a network or via a so-called packet switched access node. 6. A method of data processing for efficiently transporting a data packet according to any one of claims 1 to 5, wherein the original data packet is a normal ATM cell payload length. A method for processing data, characterized in that it comprises packets shorter than the packet length. 7. A data processing method for efficiently transporting fixed-length or variable-length data packets according to claim 5 or 6, wherein said CPCS
The concatenation and addition to generate a Service Data Unit (SDU) payload is initiated at a boundary that is a multiple of a predetermined number of bytes from the payload start point and, if necessary, of the data packets or trailers to be concatenated. Method of data processing, characterized in that padding bytes are inserted between. 8. A data processing method for efficiently transporting a fixed-length or variable-length data packet according to the method according to claim 6 or 7, wherein said user channel identification information or user data length is A method of data processing, characterized in that a default value is defined for it. 9. The data processing method according to claim 8, wherein the default value is changed based on a request from a user and confirmation by a receiving side without interruption of traffic between them, and A method of data processing, characterized in that the process uses explicit values. 10. A method of data processing for efficiently transmitting data packets over an ATM data network, the CPCS for indicating that a data packet has been transferred according to the method of claims 3-8. PDU
A method of data processing, characterized in that a so-called service trailer offset (STO) field in the trailer field is used, whereby the presence of the trailer and its length are specified. 11. An ATM according to the method of claim 10.
A method for efficiently receiving a data packet transmitted through a network, characterized in that a coded value in the service trailer offset field is monitored to control a receiving operation. Method of processing. 12. A method for efficiently transmitting or receiving a data packet according to any one of claims 3 to 11, comprising the user data length (UDL) and the user channel identification information (CID). A method of data processing, characterized in that the coded fields for a) are defined to be mutually exclusive according to the so-called basic coding rules. 13. A method for efficiently transmitting and receiving multimedia data packets according to the method of claim 12, wherein the transmission is performed in a multiplexed mode,
Characterized in that a predetermined code is specified in the CPCS PDU trailer which specifies whether it is done in blocking mode, in these two modes, or not in either of these two modes. How to process data.